Nonylcyclohexylphosphite ester polyolefin stabilizers

ABSTRACT

The present invention discloses mono-, bis- and tris-nonylcyclohexylphosphite esters, polyolefin compositions stabilized against the deleterious effects of melt processing, heat aging and exposure to combustion products of natural gas which comprise the nonylcyclohexylphosphite esters as stabilizers, and a process towards stabilizing polyolefin compositions by incorporating in or applying thereto the nonylcyclohexylphosphite esters.

This application claims benefit under 35 USC 119(e) of U.S. provisionalapplication No. 60/557,231, filed Mar. 29, 2004.

The present invention is aimed at mono-, bis- andtris-nonylcyclohexylphosphite esters and a method for stabilizingpolyolefins therewith.

BACKGROUND

Organic phosphorus compounds are well known polymer process stabilizers.For Example, Plastics Additives Handbook, 4^(th) Ed., R. Gaechter, H.Mueller, Eds., 1993, pages 40-71, discusses the stabilization ofpolypropylene (PP) and polyethylene (PE).

Known phosphite and phosphonite stabilizers include for exampletriphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkylphosphites, tris(nonylphenyl) phosphite, trilauryl phosphite,trioctadecyl phosphite, distearyl pentaerythritol diphosphite,tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-α-cumylphenyl)pentaerythrtitol diphosphite, diisodecyl pentaerythritol diphosphite,bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (D),bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (E),bisisodecyloxy-pentaerythritol diphosphite,bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite,bis(2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite, tristearylsorbitol triphosphite, tetrakis (2,4-di-tert-butylphenyl)4,4′-biphenylene-diphosphonite (H),6-isooctyloxy-2,4,8,10-tetra-tert-butyl-dibenzo[d,f][1,3,2]dioxaphosphepin(C),6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzo[d,g][1,3,2]dioxaphosphocin(A), bis(2,4-di-tert-butyl-6-methylphenyl) methyl phosphite,bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite (G),2,2′,2″-nitrilo[triethyltris(3,3′5,5′-tetra-tert-butyl-1,1′-biphenyl-2,2′-diyl)phosphite](B), bis(2,4-di-t-butylphenyl) octylphosphite,poly(4,4′-{2,2′-dimethyl-5,5′-di-t-butylphenylsulfide-}octylphosphite),poly(4,4′{-isopropylidenediphenol}-octylphosphite),poly(4,4′-{isopropylidenebis[2,6-dibromophenol]}-octylphosphite),poly(4,4′-{2,2′-dimethyl-5,5′-di-t-butylphenylsulfide}-pentaerythrityldiphosphite),

Known organic phosphorus stabilizers are also disclosed for example inU.S. Pat. No. 6,541,549 and U.S. patent application Ser. No.2003/0096890.

U.S. Pat. No. 3,756,906 discloses phosphite esters as stabilizers forpolyester-reinforced rubbers.

SUMMARY

Disclosed are mono-, bis- and tris-nonylcyclohexylphosphite esters ofthe formula I, II, III or IV

-   -   where R and R′ are independently straight or branched chain        alkyl of from 1 to 24 carbon atoms, or R and R′ together form a        5 or 6 membered ring, where the carbon atoms of said ring are        unsubstituted or substituted by one or two straight or branched        chain alkyl groups of from 1 to 24 carbon atoms.

Also disclosed is a polyolefin composition stabilized against thedeleterious effects of melt processing, heat aging and exposure tocombustion products of natural gas, which composition comprises

at least one polyolefin and

an effective stabilizing amount of one or more mono-, bis- ortris-nonylcyclohexylphosphite esters of the formula I, II, III or IV.

Also subject of this invention is a process for stabilizing a polyolefincomposition against the deleterious effects of melt processing, heataging and exposure to combustion products of natural gas, which processcomprises

-   -   incorporating into or applying to said polyolefin composition an        effective stabilizing amount of one or more mono-, bis- or        tris-nonylcyclohexylphosphite esters of the formula I, II, III        or IV.

DETAILED DISCLOSURE

Nonylcyclohexanol is available for example via catalytic hydrogenationof nonylphenol (CAS#25154-52-3). Nonylphenol is a technical grademixture of monoalkyl phenols, predominately para substituted. The alkylchains are isomeric branched-alkyl groups. The manufacture ofnonylphenol is disclosed for example in Faith, Keyes and Clark,sIndustrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds.,Wiley-Interscience, New York, 4^(th) ed., 1975, pp. 575-578. See MerckIndex 11,6599.

Tris-nonylcyclohexylphosphite is prepared by reacting three equivalentsof nonylcyclohexanol with phosporus trichloride in the absence ofoxygen, for example under a nitrogen atmosphere, and in the presence ofan acid scavenger such as triethylamine.

The mono- and bis-nonylcyclohexylphosphite esters are likewise preparedby known methods using nonylcyclohexanol and appropriate other alkylalcohol(s).

Esters of the formula I are for example

Alkyl is linear or branched and is for example methyl, ethyl, propyl,isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl,heptyl, 2,4,4-trimethylpentyl, 2-ethylhexyl, octyl, nonyl, decyl,undecyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl,octadecyl, nonadecyl or icosyl.

For example, alkyl is methyl, ethyl or hexyl.

Examples for polyolefins are:

1. Polymers of monoolefins and diolefins, for example polypropylene,polyisobutylene, polybut-1-ene, poly-4-methylpent-1-ene, polyisoprene orpolybutadiene, as well as polymers of cycloolefins, for instance ofcyclopentene or norbornene, polyethylene (which optionally can becrosslinked), for example high density polyethylene (HDPE), high densityand high molecular weight polyethylene (HDPE-HMW), high density andultrahigh molecular weight polyethylene (HDPE-UHMW), medium densitypolyethylene (MDPE), low density polyethylene (LDPE), linear low densitypolyethylene (LLDPE), (VLDPE) and (ULDPE).

Polyolefins, i.e. the polymers of monoolefins exemplified in thepreceding paragraph, for example polyethylene and polypropylene, can beprepared by different, and especially by the following, methods:

i) radical polymerization (normally under high pressure and at elevatedtemperature).

ii) catalytic polymerization using a catalyst that normally contains oneor more than one metal of groups IVb, Vb, VIb or VIII of the PeriodicTable. These metals usually have one or more than one ligand, typicallyoxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenylsand/or aryls that may be either p- or s-coordinated. These metalcomplexes may be in the free form or fixed on substrates, typically onactivated magnesium chloride, titanium (III) chloride, alumina orsilicon oxide. These catalysts may be soluble or insoluble in thepolymerization medium. The catalysts can be used by themselves in thepolymerization or further activators may be used, typically metalalkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metalalkyloxanes, said metals being elements of groups Ia, IIa and/or IIIa ofthe Periodic Table. The activators may be modified conveniently withfurther ester, ether, amine or silyl ether groups. These catalystsystems are usually termed Phillips, Standard Oil Indiana, Ziegler(-Natta), TNZ (DuPont), metallocene or single site catalysts (SSC).

2. Mixtures of the polymers mentioned under 1.), for example mixtures ofpolypropylene with polyisobutylene, polypropylene with polyethylene (forexample PP/HDPE, PP/LDPE) and mixtures of different types ofpolyethylene (for example LDPE/HDPE).

3. Copolymers of monoolefins and diolefins with each other or with othervinyl monomers, for example ethylene/propylene copolymers, linear lowdensity polyethylene (LLDPE) and mixtures thereof with low densitypolyethylene (LDPE), propylene/but-1-ene copolymers,propylene/isobutylene copolymers, ethylene/but-1-ene copolymers,ethylene/hexene copolymers, ethylene/methylpentene copolymers,ethylene/heptene copolymers, ethylene/octene copolymers,propylene/butadiene copolymers, isobutylene/isoprene copolymers,ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylatecopolymers, ethylene/vinyl acetate copolymers and their copolymers withcarbon monoxide or ethylene/acrylic acid copolymers and their salts(ionomers) as well as terpolymers of ethylene with propylene and a dienesuch as hexadiene, dicyclopentadiene or ethylidene-norbornene; andmixtures of such copolymers with one another and with polymers mentionedin 1) above, for example polypropylene/ethylene-propylene copolymers,LDPE/ethylene-vinyl acetate copolymers (EVA), LDPE/ethylene-acrylic acidcopolymers (EAA), LLDPE/EVA, LLDPE/EAA and alternating or randompolyalkylene/carbon monoxide copolymers and mixtures thereof with otherpolymers, for example polyamides.

4. Blends of polymers mentioned under 1.) with impact modifiers such asethylene-propylene-diene monomer copolymers (EPDM), copolymers ofethylene with higher alpha-olefins (such as ethylene-octene copolymers),polybutadiene, polyisoprene, styrene-butadiene copolymers, hydrogenatedstyrene-butadiene copolymers, styrene-isoprene copolymers, hydrogenatedstyrene-isoprene copolymers. These blends are commonly referred to inthe industry as TPO's (thermoplastic polyolefins).

Polyolefins of the present invention are for example polypropylene homo-and copolymers and polyethylene homo- and copolymers. For instance,polypropylene, high density polyethylene (HDPE), linear low densitypolyethylene (LLDPE) and polypropylene random and impact (heterophasic)copolymers. Preferred polyolefins of the present invention includepolypropylene homopolymers, polypropylene impact (heterophasic)copolymers, blends thereof, and TPO's such as blends of polypropylenehomopolymers and impact copolymers with EPDM or ethylene-alpha-olefincopolymers.

Melt processing techniques are know and include for example extrusion,co-kneading, pultrusion, injection molding, co-extrusion, fiberextrusion, fiber spinning, film extrusion (cast, blown, blowmolding),rotational molding, and the like.

The present nonylcyclohexylphosphite esters are used for example, inamounts of from about 0.01% to about 5% by weight, based on the weightof the polyolefin, from about 0.025% to about 1%, from about 0.05% toabout 0.5% by weight, from about 0.01% to about 1%, about 0.01% to about0.5%, about 0.025% to about 5%, or about 0.05% to about 5% by weight,based on the weight of the polyolefin to be stabilized. For example, thepresent nonylcyclohexylphosphite esters are present at a level of lessthan about 3% by weight, based on the weight of the polyolefin, or fromabout 0.01% to about 2.5% by weight, or from about 0.01% to about 2% byweight, based on the weight of the polyolefin.

The incorporation of the present nonylcyclohexylphosphite esters andoptional further additives into the polyolefin is carried out by knownmethods, for example before or after molding or also by applying thedissolved or dispersed stabilizer or stabilizer mixture to thepolyolefin, with or without subsequent evaporation of the solvent. Thestabilizer or stabilizer mixture can also be added to the polyolefins tobe stabilized in the form of a masterbatch which contains thenonylcyclohexylphosphite esters and optional additives in aconcentration of, for example, about 2.5% to about 60% by weight.

The nonylcyclohexylphosphite esters and optional further additives canalso be added before or during the polymerization or beforecrosslinking.

The present nonylcyclohexylphosphite esters and optional furtheradditives can be incorporated into the polyolefin to be stabilized inpure form or encapsulated in waxes, oils or polymers.

The present nonylcyclohexylphosphite esters and optional furtheradditives can also be sprayed onto the polyolefin to be stabilized. Itis able to dilute other additives (for example other conventionaladditives discussed further) or their melts so that it can be sprayedalso together with these additives onto the polyolefin to be stabilized.Addition by spraying during the deactivation of the polymerizationcatalysts is particularly advantageous, it being possible to carry outspraying using, for example, the steam used for deactivation.

In the case of spherically polymerized polyolefins it may, for example,be advantageous to apply the present stabilizer optionally together withother additives, by spraying.

The polyolefin compositions according to the instant invention areuseful in the manufacture of polyolefin articles. The said articles arefor example woven fibers, non-woven fibers, films, sheets or moldedarticles.

Further stabilizers include for example hindered phenolic antioxidants,hindered amine light stabilizers, hydroxylamine stabilizers, amine oxidestabilizers, benzofuranone stabilizers and other organic phosphorusstabilizers.

Hindered phenolic antioxidants include for exampletris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate,1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,the calcium salt of the monoethyl ester of3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid, pentaerythritoltetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] or octadecyl3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

Hindered amine light stabilizers include for example

where n is an integer such that the total molecular weight is aboveabout 1000 g/mole.

Hydroxylamine stabilizers are for example N,N-dibenzylhydroxylamine,N,N-diethylhydroxylamine, N,N-dioctylhydroxylamine,N,N-dilaurylhydroxylamine, N,N-didodecylhydroxylamine,N,N-ditetradecylhydroxylamine, N,N-dihexadecylhydroxylamine,N,N-dioctadecylhydroxylamine, N-hexadecyl-N-tetradecylhydroxylamine,N-hexadecyl-N-heptadecylhydroxylamine,N-hexadecyl-N-octadecylhydroxylamine,N-heptadecyl-N-octadecylhydroxylamine, N-methyl-N-octadecylhydroxylamineor N,N-di(hydrogenated tallow)hydroxylamine.

The amine oxide stabilizer is for example Genox™ EP, a di(C₁₆-C₁₈)alkylmethyl amine oxide, CAS# 204933-93-7.

Benzofuranone stabilizers are for example3-(4-(2-acetoxyethoxy)phenyl)-5,7-di-tert-butyl-benzofuran-2-one,5,7-di-tert-butyl-3-(4-(2-stearoyloxyethoxy)phenyl)benzofuran-2-one,3,3′-bis(5,7-di-tert-butyl-3-(4-(2-hydroxyethoxy)phenyl)benzofuran-2-one),5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one,3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,4-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one or3-(2,3-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one.

Further organic phosphorus stabilizers are for example those asdisclosed previously. Further organic phosphorus stabilizers are alsofor example those as disclosed in U.S. Pat. No. 6,541,549 and U.S.patent application Ser. No. 2003/0096890, the disclosures of which arehereby incorporated by reference.

These optional stabilizers are employed at the same levels as thepresent nonylcyclohexylphosphite esters.

In addition to the nonylcyclohexylphosphite esters and the aboveoptional stabilizers, the following further additives may also beemployed. These further stabilizers are employed for example at uselevels from about 0.01% to about 5% by weight, based on the weight ofthe polyolefin.

1. Antioxidants

-   -   1.1. Alkylated monophenols, for example        2,6-di-tert-butyl-4-methylphenol,        2-tert-butyl-4,6-dimethylphenol,        2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butyl        phenol, 2,6-di-tert-butyl-4-isobutylphenol,        2,6-dicyclopentyl-4-methylphenol,        2-(α-methylcyclohexyl)-4,6-dimethylphenol,        2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol,        2,6-di-tert-butyl-4-methoxymethylphenol, nonylphenols which are        linear or branched in the side chains, for example,        2,6-di-nonyl-4-methylphenol,        2,4-dimethyl-6-(1-methylundec⁻¹-yl)phenol,        2,4-dimethyl-6-(1-methylheptadec⁻¹-yl)phenol,        2,4-dimethyl-6-(1-methyltridec⁻¹-yl)phenol and mixtures thereof.    -   1.2. Alkylthiomethylphenols, for example        2,4-dioctylthiomethyl-6-tert-butylphenol,        2,4-dioctylthiomethyl-6-methylphenol,        2,4-dioctylthiomethyl-6-ethylphenol,        2,6-di-dodecylthiomethyl-4-nonylphenol.    -   1.3. Hydroquinones and alkylated hydroquinones, for example        2,6-di-tert-butyl-4-methoxyphenol,        2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone,        2,6-diphenyl-4-octadecyloxyphenol,        2,6-di-tert-butylhydroquinone,        2,5-di-tert-butyl-4-hydroxyanisole,        3,5-di-tert-butyl-4-hydroxyanisole,        3,5-di-tert-butyl-4-hydroxyphenyl stearate,        bis-(3,5-di-tert-butyl-4-hydroxyphenyl) adipate.    -   1.4. Tocopherols, for example α-tocopherol, β-tocopherol,        γ-tocopherol, δ-tocopherol and mixtures thereof (Vitamin E).    -   1.5. Hydroxylated thiodiphenyl ethers, for example        2,2′-thiobis(6-tert-butyl-4-methylphenol),        2,2′-thiobis(4-octylphenol),        4,4′-thiobis(6-tert-butyl-3-methylphenol),        4,4′-thiobis(6-tert-butyl-2-methylphenol),        4,4′-thiobis-(3,6-di-sec-amylphenol),        4,4′-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide.    -   1.6. Alkylidenebisphenols, for example        2,2′-methylenebis(6-tert-butyl-4-methylphenol),        2,2′-methylenebis(6-tert-butyl-4-ethylphenol),        2,2′-methylenebis[4-methyl-6-α-methylcyclohexyl)phenol],        2,2′-methylenebis(4-methyl-6-cyclohexylphenol),        2,2′-methylenebis(6-nonyl-4-methylphenol),        2,2′-methylenebis(4,6-di-tert-butylphenol),        2,2′-ethylidenebis(4,6-di-tert-butylphenol),        2,2′-ethylidenebis(6-tert-butyl-4-isobutylphenol),        2,2′-methylenebis[6-α-methylbenzyl)-4-nonylphenol],        2,2′-methylenebis[6-(α,α-dimethylbenzyl)-4-nonylphenol],        4,4′-methylenebis(2,6-di-tert-butylphenol),        4,4′-methylenebis(6-tert-butyl-2-methylphenol),        1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,        2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol,        1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,        1,1-bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane,        ethylene glycol        bis[3,3-bis(3-tert-butyl-4-hydroxyphenyl)butyrate],        bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadiene,        bis[2-(3′tert-butyl-2-hydroxy-5-methylbenzyl)-6-tert-butyl-4-methylphenyl]terephthalate,        1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)butane,        2,2-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)propane,        2,2-bis-(5-tert-butyl-4-hydroxy2-methylphenyl)-4-n-dodecylmercaptobutane,        1,1,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane.    -   1.7. Benzyl compounds, for example        3,5,3′,5′-tetra-tert-butyl4,4′-dihydroxydibenzyl ether,        octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate,        tridecyl-4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate,        tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine,        1,3,5-tri-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,        di-(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide,        3,5-di-tert-butyl-4-hydroxybenzyl-mercapto-acetic acid isooctyl        ester, bis-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithiol        terephthalate, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)        isocyanurate,        1,3,5-tris-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)        isocyanurate, 3,5-di-tert-butyl-4-hydroxybenzyl-phosphoric acid        dioctadecyl ester and        3,5-di-tert-butyl-4-hydroxybenzyl-phosphoric acid monoethyl        ester, calcium-salt.    -   1.8. Hydroxybenzylated malonates, for example        dioctadecyl-2,2-bis-(3,5-di-tert-butyl-2-hydroxybenzyl)-malonate,        di-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)-malonate,        di-dodecylmercaptoethyl-2,2-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate,        bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate.    -   1.9. Aromatic hydroxybenzyl compounds, for example        1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,        1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene,        2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.    -   1.10. Triazine compounds, for example        2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine,        2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine,        2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine,        2,4,6-tris-(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine,        1,3,5-tris-(3,5-di-tert-butyl-4-hydroxy-benzyl)isocyanurate,        1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate,        2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine,        1,3,5-tris(3,5-di-tert-butyl-4-hydroxy-phenylpropionyl)-hexahydro-1,3,5-triazine,        1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate.    -   1.11. Benzylphosphonates, for example        dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate,        diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate,        dioctadecyl3,5-di-tert-butyl-4-hydroxybenzylphosphonate,        dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate,        the calcium salt of the monoethyl ester of        3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.    -   1.12. Acylaminophenols, for example 4-hydroxy-lauric acid        anilide, 4-hydroxy-stearic acid anilide,        2,4-bis-octylmercapto-6-(3,5-tert-butyl-4-hydroxyanilino)-s-triazine        and octyl-N-(3,5-di-tert-butyl-4-hydroxyphenyl)-carbamate.    -   1.13. Esters of β-(3.5-di-tert-butyl-4-hydroxyphenyl)propionic        acid with mono- or polyhydric alcohols, e.g. with methanol,        ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol,        1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl        glycol, thiodiethylene glycol, diethylene glycol, triethylene        glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate,        N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol,        3-thiapentadecanol, trimethylhexanediol, trimethylolpropane,        4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.    -   1.14. Esters of        β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with        mono- or polyhydric alcohols, e.g. with methanol, ethanol,        n-octanol, i-octanol, octadecanol, 1,6-hexane-diol,        1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl        glycol, thiodiethylene glycol, diethylene glycol, triethylene        glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate,        N,N′-bis-(hydroxyethyl)oxamide, 3-thiaundecanol,        3-thiapentadecanol, trimethylhexanediol, trimethyl-olpropane,        4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.    -   1.15. Esters of β-(3.5-dicyclohexyl-4-hydroxyphenyl)propionic        acid with mono- or polyhydric alcohols, e.g. with methanol,        ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol,        ethylene glycol, 1,2-propanediol, neopentyl glycol,        thiodiethylene glycol, diethylene glycol, triethylene glycol,        pentaerythritol, tris(hydroxyethyl)isocyanurate,        N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol,        3-thiapentadecanol, trimethylhexanediol, trimethylolpropane,        4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.    -   1.16. Esters of 3.5-di-tert-butyl-4-hydroxyphenyl acetic acid        with mono- or polyhydric alcohols, e.g. with methanol, ethanol,        octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene        glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene        glycol, diethylene glycol, triethylene glycol, pentaerythritol,        tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)ox-amide,        3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,        trimethylolpropane,        4-hy-droxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.    -   1.17. Amides of β-(3.5-di-tert-butyl-4-hydroxyphenyl)Propionic        acid e.g.        N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamide,        N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamide,        N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazide,        N,N′-bis[2-(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide        (Naugard®XL-1 supplied by Uniroyal).    -   1.18. Ascorbic Acid (Vitamin C)    -   1.19. Aminic antioxidants, for example        N,N′-di-isopropyl-p-phenylenediamine,        N,N′-di-sec-butyl-p-phenylenediamine,        N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine,        N,N′-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine,        N,N′-bis(1-methylheptyl)-p-phenylenediamine,        N,N′-dicyclohexyl-p-phenylenediamine,        N,N′-diphenyl-p-phenylenediamine,        N,N′-bis(2-naphthyl)-p-phenylenediamine,        N-isopropyl-N′-phenyl-p-phenylenediamine,        N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine,        N-(1-methylheptyl)-N′-phenyl-p-phenylenediamine,        N-cyclohexyl-N′-phenyl-p-phenlenediamine,        4-(p-toluenesulfamoyl)diphenylamine,        N,N′-dimethyl-N,N′-di-sec-butyl-p-phenylenediamine,        diphenylamine, N-allyldiphenylamine, 4-isopropoxydiphenylamine,        N-phenyl-1-naphthylamine,        N-(4-tert-octylphenyl)-1-naphthylamine,        N-phenyl-2-naphthylamine, octylated diphenylamine, for example        p,p′-di-tert-octyldiphenylamine, 4-n-butylaminophenol,        4-butyrylaminophenol, 4-nonanoylaminophenol,        4-dodecanoylaminophenol, 4-octadecanoylaminophenol,        bis(4-methoxyphenyl)amine,        2,6-di-tert-butyl-4-dimethylaminomethylphenol,        2,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane,        N,N,N′,N′-tetramethyl-4,4′-diaminodiphenylmethane,        1,2-bis[(2-methylphenyl)amino]ethane,        1,2-bis(phenylamino)propane, (o-tolyl)biguanide,        bis[4-(1′,3′-dimethylbutyl)phenyl]amine, tert-octylated        N-phenyl-1-naphthylamine, a mixture of mono- and dialkylated        tert-butyl/tert-octyl-diphenylamines, a mixture of mono- and        dialkylated nonyldiphenylamines, a mixture of mono- and        dialkylated dodecyidiphenylamines, a mixture of mono- and        dialkylated isopropyl/isohexyldiphenylamines, a mixture of mono-        and dialkylated tert-butyldiphenylamines,        2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, a        mixture of mono- and dialkylated        tert-butyl/tert-octylphenothiazines, a mixture of mono- and        dialkylated tert-octyl-phenothiazines, N-allylphenothiazin,        N,N,N′,N′-tetraphenyl-1,4-diaminobut-2-ene,        N,N-bis-(2,2,6,6-tetramethyl-piperid-4-yl-hexamethylenediamine,        bis(2,2,6,6-tetramethylpiperid-4-yl)-sebacate,        2,2,6,6-tetramethylpiperidin-4-one,        2,2,6,6-tetramethylpiperidin-4-ol.

2. UV Absorbers and Light Stabilizers

-   -   2.1. 2-(2-Hydroxyphenyl)-2H-benzotriazoles, for example known        commercial hydroxyphenyl-2H-benzotriazoles and benzotriazoles as        disclosed in, U.S. Pat. Nos. 3,004,896; 3,055,896; 3,072,585;        3,074,910; 3,189,615; 3,218,332; 3,230,194; 4,127,586;        4,226,763; 4,275,004; 4,278,589; 4,315,848; 4,347,180;        4,383,863; 4,675,352; 4,681,905, 4,853,471; 5,268,450;        5,278,314; 5,280,124; 5,319,091; 5,410,071; 5,436,349;        5,516,914; 5,554,760; 5,563,242; 5,574,166; 5,607,987, 5,977,219        and 6,166,218 such as        2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole,        2-(3,5-di-t-butyl-2-hydroxyphenyl)-2H-benzotriazole,        2-(2-hydroxy-5-t-butylphenyl)-2H-benzotriazole,        2-(2-hydroxy-5-t-octylphenyl)-2H-benzotriazole,        5-chloro-2-(3,5-di-t-butyl-2-hydroxyphenyl)-2H-benzotriazole,        5-chloro-2-(3-t-butyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole,        2-(3-sec-butyl-5-t-butyl-2-hydroxyphenyl)-2H-benzotriazole,        2-(2-hydroxy-4-octyloxyphenyl)-2H-benzotriazole,        2-(3,5-di-t-amyl-2-hydroxyphenyl)-2H-benzotriazole,        2-(3,5-bis-α-cumyl-2-hydroxyphenyl)-2H-benzotriazole,        2-(3-t-butyl-2-hydroxy-5-(2-((ω-hydroxy-octa-(ethyleneoxy)carbonyl-ethyl)-,        phenyl)-2H-benzotriazole,        2-(3-dodecyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole,        2-(3-t-butyl-2-hydroxy-5-(2-octyloxycarbonyl)ethylphenyl)-2H-benzotriazole,        dodecylated 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole,        2-(3-t-butyl-2-hydroxy-5-(2-octyloxycarbonylethyl)phenyl)-5-chloro-2H-benzotriazole,        2-(3-tert-butyl-5-(2-(2-ethylhexyloxy)-carbonylethyl)-2-hydroxyphenyl)-5-chloro-2H-benzotriazole,        2-(3-t-butyl-2-hydroxy-5-(2-methoxycarbonylethyl)phenyl)-5-chloro-2H-benzotriazole,        2-(3-t-butyl-2-hydroxy-5-(2-methoxycarbonylethyl)phenyl)-2H-benzotriazole,        2-(3-t-butyl-5-(2-(2-ethylhexyloxy)carbonylethyl)-2-hydroxyphenyl)-2H-benzotriazole,        2-(3-t-butyl-2-hydroxy-5-(2-isooctyloxycarbonylethyl)phenyl-2H-benzotriazole,        2,2′-methylene-bis(4-t-octyl-(6-2H-benzotriazol-2-yl)phenol),        2-(2-hydroxy-3-α-cumyl-5-t-octylphenyl)-2H-benzotriazole,        2-(2-hydroxy-3-t-octyl-5-α-cumylphenyl)-2H-benzotriazole,        5-fluoro-2-(2-hydroxy-3,5-di-α-cumyl-phenyl)-2H-benzotriazole,        5-chloro-2-(2-hydroxy-3,5-di-α-cumylphenyl)-2H-benzotriazole,        5-chloro-2-(2-hydroxy-3-α-cumyl-5-t-octylphenyl)-2H-benzotriazole,        2-(3-t-butyl-2-hydroxy-5-(2-isooctyloxycarbonylethyl)phenyl)-5-chloro-2H-benzotriazole,        5-trifluoromethyl-2-(2-hydroxy-3-α-cumyl-5-t-octylphenyl)-2H-benzotriazole,        5-trifluoromethyl-2-(2-hydroxy-5-t-octylphenyl)-2H-benzotriazole,        5-trifluoromethyl-2-(2-hydroxy-3,5-di-t-octylphenyl)-2H-benzotriazole,        methyl        3-(5-trifluoromethyl-2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyhydrocinnamate,        5-butylsulfonyl-2-(2-hydroxy-3-α-cumyl-5-t-octylphenyl)-2H-benzotriazole,        5-trifluoromethyl-2-(2-hydroxy-3-α-cumyl-5-t-butylphenyl)-2H-benzotriazole,        5-trifluoromethyl-2-(2-hydroxy-3,5-di-t-butylphenyl)-2H-benzotriazole,        5-trifluoromethyl-2-(2-hydroxy-3,5-di-α-cumylphenyl)-2H-benzotriazole,        5-butylsulfonyl-2-(2-hydroxy-3,5-di-t-butylphenyl)-2H-benzotriazole        and        5-phenylsulfonyl-2-(2-hydroxy-3,5-di-t-butylphenyl)-2H-benzotriazole.    -   2.2. 2-Hydroxybenzophenones, for example the 4-hydroxy,        4-methoxy, 4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy,        4,2′,4′-trihydroxy and 2′-hydroxy-4,4′-dimethoxy derivatives.    -   2.3. Esters of substituted and unsubstituted benzoic acids, as        for example 4-tert-butylphenyl salicylate, phenyl salicylate,        octylphenyl salicylate, dibenzoyl resorcinol,        bis(4-tert-butylbenzoyl) resorcinol, benzoyl resorcinol,        2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate,        hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl        3,5-di-tert-butyl-4-hydroxybenzoate,        2-methyl-4,6-di-tert-butylphenyl        3,5-di-tert-butyl-4-hydroxybenzoate.    -   2.4. Acrylates and malonates, for example,        α-cyano-β,β-diphenylacrylic acid ethyl ester or isooctyl ester,        α-carbomethoxy-cinnamic acid methyl ester,        α-cyano-α-methyl-p-methoxy-cinnamic acid methyl ester or butyl        ester, α-carbomethoxy-p-methoxy-cinnamic acid methyl ester,        N-(β-carbomethoxy-β-cyanovinyl)-2-methyl-indoline, Sanduvor®        PR25, dimethyl p-methoxybenzylidenemalonate (CAS# 7443-25-6),        and Sanduvor® PR31, di-(1,2,2,6,6-pentamethylpiperidin-4-yl)        p-methoxybenzylidenemalonate (CAS #147783-69-5).    -   2.5. Nickel compounds, for example nickel complexes of        2,2′-thio-bis-[4-(1,1,3,3-tetramethylbutyl)phenol], such as the        1:1 or 1:2 complex, with or without additional ligands such as        n-butylamine, triethanolamine or N-cyclohexyldiethanolamine,        nickel dibutyldithiocarbamate, nickel salts of the monoalkyl        esters, e.g. the methyl or ethyl ester, of        4-hydroxy-3,5-di-tert-butylbenzylphosphonic acid, nickel        complexes of ketoximes, e.g. of 2-hydroxy-4-methylphenyl        undecylketoxime, nickel complexes of        1-phenyl-4-lauroyl-5-hydroxypyrazole, with or without additional        ligands.    -   2.6. Sterically hindered amine stabilizers, for example        4-hydroxy-2,2,6,6-tetramethylpiperidine,        1-allyl-4-hydroxy-2,2,6,6-tetramethylpiperidine,        1-benzyl-4-hydroxy-2,2,6,6-tetramethylpiperidine,        bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate,        bis(2,2,6,6-tetramethyl-4-piperidyl) succinate,        bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate,        bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate,        bis(1,2,2,6,6-pentamethyl-4-piperidyl)        n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the        condensate of        1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and        succinic acid, linear or cyclic condensates of        N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine        and 4-tert-octylamino-2,6-dichloro-1,3,5-triazine,        tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate,        tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate,        1,1′-(1,2-ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone),        4-benzoyl-2,2,6,6-tetramethylpiperidine,        4-stearyloxy-2,2,6,6-tetramethylpiperidine,        bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)        malonate,        3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione,        bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) sebacate,        bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, linear        or cyclic condensates of        N,N′-bis-(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine        and 4-morpholino-2,6-dichloro-1,3,5-triazine, the condensate of        2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine        and 1,2-bis(3-amino-propylamino)ethane, the condensate of        2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazine        and 1,2-bis-(3-aminopropylamino)ethane,        8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione,        3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidin-2,5-dione,        3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione,        a mixture of 4-hexadecyloxy- and        4-stearyloxy-2,2,6,6-tetramethylpiperidine, a condensation        product of        N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine        and 4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, a        condensation product of 1,2-bis(3-aminopropylamino)ethane and        2,4,6-trichloro-1,3,5-triazine as well as        4-butylamino-2,2,6,6-tetramethylpiperidine (CAS Reg. No.        [136504-96-6]);        N-(2,2,6,6-tetramethyl-4-piperidyl)-n-dodecylsuccinimid,        N-(1,2,2,6,6-pentamethyl-4-piperidyl)-n-dodecylsuccinimid,        2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane,        a reaction product of        7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro        [4,5]decane and epichlorohydrin,        1,1-bis(1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyl)-2-(4-methoxyphenyl)ethene,        N,N′-bis-formyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine,        diester of 4-methoxy-methylene-malonic acid with        1,2,2,6,6-pentamethyl-4-hydroxypiperidine,        poly[methylpropyl-3-oxy-4-(2,2,6,6-tetramethyl-4-piperidyl)]siloxane,        reaction product of maleic acid anhydride-α-olefin-copolymer        with 2,2,6,6-tetramethyl-4-aminopiperidine or        1,2,2,6,6-pentamethyl-4-aminopiperidine.

The sterically hindered amine may also be one of the compounds describedin U.S. Pat. No. 5,980,783, the relevant parts of which are herebyincorporated by reference, that is compounds of component I-a), I-b),I-c), I-d), I-e), I-f), I-g), I-h), I-i), I-j), I-k) or I-l), inparticular the light stabilizer1-α-1,1-α-2,1-b-1,1-c-1,1-c-2,1-d-1,1-d-2,1-d-3,1-e-1,1-f-1,1-g-1,1-g-2or 1-k-1 listed on columns 64-72 of said U.S. Pat. No. 5,980,783.

The sterically hindered amine may also be one of the compounds describedin U.S. Pat. Nos. 6,046,304 and 6,297,299, the disclosures of which arehereby incorporated by reference, for example compounds as described inclaims 10 or 38 or in Examples 1-12 or D-1 to D-5 therein.

-   -   2.7. Sterically hindered amines substituted on the N-atom by a        hydroxy-substituted alkoxy group, for example compounds such as        1-(2-hydroxy-2-methylpropoxy)₄-octadecanoyloxy-2,2,6,6-tetramethylpiperidine,        1-(2-hydroxy-2-methylpropoxy)-4-hexadecanoyloxy-2,2,6,6-tetramethylpiperidine,        the reaction product of        1-oxyl-4-hydroxy-2,2,6,6-tetramethylpiperidine with a carbon        radical from t-amylalcohol,        1-(2-hydroxy-2-methylpropoxy)-4-hydroxy-2,2,6,6-tetramethylpiperidine,        1-(2-hydroxy-2-methylpropoxy)-4-oxo-2,2,6,6-tetramethylpiperidine,        bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)        sebacate,        bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)        adipate,        bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)        succinate,        bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl)        glutarate and        2,4-bis{N-[1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl]-N-butylamino}-6-(2-hydroxyethyl-amino)-s-triazine.    -   2.8. Oxamides, for example 4,4′-dioctyloxyoxanilide,        2,2′-diethoxyoxanilide,        2,2′-dioctyloxy-5,5′-di-tert-butoxanilide,        2,2′-didodecyloxy-5,5′-di-tert-butoxanilide,        2-ethoxy-2′-ethyloxanilide,        N,N′-bis(3-dimethylaminopropyl)oxamide,        2-ethoxy-5-tert-butyl-2′-ethoxanilide and its mixture with        2-ethoxy-2′-ethyl-5,4′-di-tert-butoxanilide, mixtures of o- and        p-methoxy-disubstituted oxanilides and mixtures of o- and        p-ethoxy-disubstituted oxanilides.    -   2.9. Tris-aryl-o-hydroxyphenyl-s-triazines, for example known        commercial tris-aryl-o-hydroxyphenyl-s-triazines and triazines        as disclosed in, U.S. Pat. Nos. 3,843,371; 4,619,956; 4,740,542;        5,096,489; 5,106,891; 5,298,067; 5,300,414; 5,354,794;        5,461,151; 5,476,937; 5,489,503; 5,543,518; 5,556,973;        5,597,854; 5,681,955; 5,726,309; 5,736,597; 5,942,626;        5,959,008; 5,998,116; 6,013,704; 6,060,543; 6,187,919; 6,242,598        and 6,468,958, for example        4,6-bis-(2,4-dimethylphenyl)-2-(2-hydroxy-4-octyloxyphenyl)-s-triazine,        Cyasorb® 1164, Cytec Corp,        4,6-bis-(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-s-triazine,        2,4-bis(2,4-dihydroxyphenyl)-6-(4-chlorophenyl)-s-triazine,        2,4-bis[2-hydroxy4-(2-hydroxy-ethoxy)phenyl]-6-(4-chlorophenyl)-s-triazine,        2,4-bis[2-hydroxy4-(2-hydroxy4-(2-hydroxy-ethoxy)phenyl]-6-(2,4-dimethylphenyl)-s-triazine,        2,4-bis[2-hydroxy4-(2-hydroxyethoxy)phenyl]-6-(4-bromophenyl)-s-triazine,        2,4-bis[2-hydroxy4-(2-acetoxyethoxy)phenyl]-6-(4-chlorophenyl)-s-triazine,        2,4-bis(2,4-dihydroxyphenyl)-6-(2,4-dimethylphenyl)-s-triazine,        2,4-bis(4-biphenylyl)-6-(2-hydroxy-4-octyloxycarbonylethylideneoxyphenyl)-s-triazine,        2-phenyl-4-[2-hydroxy-4-(3-sec-butyloxy-2-hydroxypropyloxy)phenyl]-6-[2-hydroxy4-(3-sec-amyloxy-2-hydroxypropyloxy)-phenyl]-s-triazine,        2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-benzyloxy-2-hydroxy-propyloxy)phenyl]-s-triazine,        2,4-bis(2-hydroxy-4-n-butyloxyphenyl)-6-(2,4-di-n-butyloxyphenyl)-s-triazine,        2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-nonyloxy*-2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine        (* denotes a mixture of octyloxy, nonyloxy and decyloxy groups),        methylenebis-{2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-butyloxy-2-hydroxypropoxy)-phenyl]-s-triazine},        methylene bridged dimer mixture bridged in the 3:5′, 5:5′ and        3:3′ positions in a 5:4:1 ratio,        2,4,6-tris(2-hydroxy-4-isooctyloxycarbonylisopropylideneoxyphenyl)-s-triazine,        2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-hexyloxy-5-α-cumylphenyl)-s-triazine,        2-(2,4,6-trimethyl-phenyl)-4,6-bis[2-hydroxy-4-(3-butyloxy-2-hydroxypropyloxy)phenyl]-s-triazine,        2,4,6-tris[2-hydroxy-4-(3-sec-butyloxy-2-hydroxypropyloxy)phenyl]-s-triazine,        mixture of        4,6-bis-(2,4-dimethylphenyl)-2-(2-hydroxy-4-(3-dodecyloxy-2-hydroxypropoxy)-phenyl)-s-triazine        and        4,6-bis-(2,4-dimethylphenyl)-2-(2-hydroxy-4-(3-tridecyloxy-2-hydroxypropoxy)-phenyl)-s-triazine,        4,6-bis-(2,4-dimethylphenyl)-2-(2-hydroxy-4-(3-(2-ethylhexyloxy)-2-hydroxypropoxy)-phenyl)-s-triazine        and 4,6-diphenyl-2-(4-hexyloxy-2-hydroxyphenyl)-s-triazine.

3. Metal deactivators, for example N,N′-diphenyloxamide,N-salicylal-N′-salicyloyl hydrazine, N,N′-bis(salicyloyl) hydrazine,N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hydrazine,3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyl dihydrazide,oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenylhydrazide,N,N′-diacetyladipoyl dihydrazide, N,N′-bis(salicyloyl)oxalyldihydrazide, N,N′-bis(salicyloyl)thiopropionyl dihydrazide.

4. Phosphites and phosphonites, for example triphenyl phosphite,diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, distearylpentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite,diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite,bis(2,6-di-tert-butyl-4-methylphenyl)-pentaerythritol diphosphite,diisodecyloxypentaerythritol diphosphite,bis(2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite,bis(2,4,6-tris(tert-butylphenyl)pentaerythritol diphosphite, tristearylsorbitol triphosphite, tetrakis(2,4-di-tert-butylphenyl)4,4′-biphenylene diphosphonite,6-isooctyloxy-2,4,8,10-tetra-tert-butyl-dibenzo[d,f][1,3,2]dioxaphosphepin,6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzo[d,g][1,3,2]dioxaphosphocin,bis(2,4-di-tert-butyl-6-methylphenyl) methyl phosphite,bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite,2,2′,2″-nitrilo[triethyltris(3,3′,5,5′-tetra-tert-butyl-1,1′-biphenyl-2,2′-diyl)phosphite],2-ethylhexyl(3,3′,5,5′-tetra-tert-butyl-1,1′-biphenyl-2,2′-diyl)phosphite.

Especially preferred are the following phosphites:

Tris(2,4-di-tert-butylphenyl) phosphite, tris(nonylphenyl) phosphite,

5. Hydroxylamines, for example N,N-dibenzylhydroxylamine,N,N-diethylhydroxylamine, N,N-dioctylhydroxylamine,N,N-dilaurylhydroxylamine, N,N-ditetradecylhydroxylamine,N,N-dihexadecylhydroxylamine, N,N-dioctadecylhydroxylamine,N-hexadecyl-N-octadecylhydroxyl-amine,N-heptadecyl-N-octadecylhydroxylamine, N-methyl-N-octadecylhydroxylamineand the N,N-dialkylhydroxylamine derived from hydrogenated tallow amine.

6. Nitrones, for example N-benzyl-α-phenylnitrone,N-ethyl-α-methylnitrone, N-octyl-α-heptylnitrone,N-lauryl-α-undecyInitrone, N-tetradecyl-α-tridcyinitrone,N-hexadecyl-α-pentadecyInitrone, N-octadecyl-α-heptadecyInitrone,N-hexadecyl-α-heptadecyInitrone, N-ocatadecyl-α-pentadecyInitrone,N-heptadecyl-α-heptadecyinitrone, N-octadecyl-α-hexadecyInitrone,N-methyl-α-heptadecyInitrone and the nitrone derived fromN,N-dialkylhydro-xylamine derived from hydrogenated tallow amine.

7. Amine oxides, for example amine oxide derivatives as disclosed inU.S. Pat. Nos. 5,844,029 and 5,880,191, didecyl methyl amine oxide,tridecyl amine oxide, tridodecyl amine oxide and trihexadecyl amineoxide.

8. Benzofuranones and indolinones, for example those disclosed in U.S.Pat. Nos. 4,325,863, 4,338,244, 5,175,312, 5,216,052, 5,252,6435,369,159 5,356,966 5,367,008 5,428,177 or 5,428,162 or3-[4-(2-acetoxyethoxy)phenyl]-5,7-di-tert-butyl-benzofuran-2-one,5,7-di-tert-butyl-3-[4-(2-stearoyloxyethoxy)phenyl]benzofuran-2-one,3,3′-bis[5,7-di-tert-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one],5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one,3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,4-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one, Irganox®HP-136, Ciba Specialty Chemicals Corp., and3-(2,3-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one.

9. Thiosynergists, for example dilauryl thiodipropionate or distearylthiodipropionate.

10. Peroxide scavengers, for example esters of β-thiodipropionic acid,for example the lauryl, stearyl, myristyl or tridecyl esters,mercaptobenzimidazole or the zinc salt of 2-mercapto-benzimidazole, zincdibutyldithiocarbamate, dioctadecyl disulfide, pentaerythritoltetrakis(β-dodecylmercapto)propionate.

11. Basic co-stabilizers, for example melamine, polyvinylpyrrolidone,dicyandiamide, triallyl cyanurate, urea derivatives, hydrazinederivatives, amines, polyamides, polyurethanes, alkali metal salts andalkaline earth metal salts of higher fatty acids, for example, calciumstearate, zinc stearate, magnesium behenate, magnesium stearate, sodiumricinoleate and potassium palmitate, antimony pyrocatecholate or zincpyrocatecholate.

12. Nucleating agents, for example inorganic substances such as talcum,metal oxides such as titanium dioxide or magnesium oxide, phosphates,carbonates or sulfates of, preferably, alkaline earth metals; organiccompounds such as mono- or polycarboxylic acids and the salts thereof,e.g. 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid, sodiumsuccinate or sodium benzoate; polymeric compounds such as ioniccopolymers (ionomers).

13. Fillers and reinforcing agents, for example calcium carbonate,silicates, glass fibres, glass bulbs, asbestos, talc, kaolin, mica,barium sulfate, metal oxides and hydroxides, carbon black, graphite,wood flour and flours or fibers of other natural products, syntheticfibers.

14. Dispersing Agents, such as polyethylene oxide waxes or mineral oil.

15. Other additives, for example plasticizers, lubricants, emulsifiers,pigments, dyes, optical brighteners, rheology additives, catalysts,flow-control agents, slip agents, crosslinking agents, crosslinkingboosters, halogen scavengers, smoke inhibitors, flameproofing agents,antistatic agents, clarifiers such as substituted and unsubstitutedbisbenzylidene sorbitols, benzoxazinone UV absorbers such as2,2′-p-phenylene-bis(3,1-benzoxazin4-one), Cyasorb® 3638 (CAS#18600-59-4), and blowing agents.

The fillers and reinforcing agents (item 9 in the list), for exampletalc, calcium carbonate, mica or kaolin, are added to the polyolefins inconcentrations of about 0.01% to about 40% by weight, based on theoverall weight of the polyolefins to be stabilized.

The fillers and reinforcing agents (item 9 in the list), for examplemetal hydroxides, especially aluminum hydroxide or magnesium hydroxide,are added to the polyolefins in concentrations of about 0.01% to about60% by weight, based on the overall weight of the polyolefins to bestabilized.

Carbon black as filler is added to the polyolefins in concentrations,judiciously, of from about 0.01% to about 5% by weight, based on theoverall weight of the polyolefins to be stabilized.

Glass fibers as reinforcing agents are added to the polyolefins inconcentrations, judiciously, of from about 0.01% to about 20% by weight,based on the overall weight of the polyolefins to be stabilized.

The following Examples illustrate the invention in more detail. Partsand percentages are by weight unless otherwise indicated.

The formulations in the Examples employ the following compounds:

AO1 is pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate],

AO2 is octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate,

P1 is tris(2,4-di-tert-butylphenyl) phosphite,

P2 is tetrakis (2,4-di-tert-butylphenyl) 4,4′-biphenylene-diphosphonite,

P3 is bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite,

P5 is tris-nonylcyclohexylphosphite (subject of the invention),

P6 is tris-nonylphenylphosphite (TNPP),

P7 is bis(2,4-di-tert-butylphenyl-6-methyl) ethylphosphite,

P8 is bis(2,4-di-cumyl) pentaerythritol diphosphite,

BF1 is Irganoxe HP-136,3-(3,4-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one,

NOH is an N,N-di(alkyl)hydroxylamine produced by the direct oxidation ofN,N-di(hydrogenated tallow)amine, prepared in the working Examples ofU.S. Pat. No. 5,013,510,

AOx is a di(C₁₆-C₁₈)alkyl methyl amine oxide, CAS# 204933-93-7.

EXAMPLE 1 Preparation of Tris-Nonylcyclohexylphosphite

A solution of nonylcyclohexanol (29.5 g, 0.13 mol) and triethylamine (20ml, 0.14 mol) in dry toluene (300 ml) is degassed by bubbling nitrogenthrough the solution for 5 minutes. The solution is then cooled to 0° C.in an ice bath and phosphorous trichloride (6 g, 0.043 mol) in dry,degassed toluene (50 ml) is added dropwise over 1 hour. The mixture isthen allowed to come to room temperature and is heated to 60° C. for 2hours. The mixture is cooled, filtered and the toluene removed underreduced pressure to afford a viscous oil (30 g, 100%). P³¹ NMR shows 3P(III) species 139.3, 139.4 and 140.9 ppm. H¹ NMR is consistent.

EXAMPLE 2 Preparation of5-butyl-5-ethyl-2-(4-nonyl-cyclohexyloxy)-1,3,2-dioxaphosphorinane

To a solution of 28 g (0.17 mole) of 2-butyl-2-ethyl-1,3-propandiol in300 mL of toluene is added dropwise 16 mL (0.17 mole) of phosphorustrichloride at 70° C. After 1 h, the P³¹-NMR shows that the PCl₃ (signalat 220 ppm) is fully reacted and a new product is formed (signal at 150ppm). The temperature is raised to 80° C. At this temperature a solutionof 35.8 g (0.17 mole) 4-nonylcyclohexanol, 200 mL (1.4 mole) oftriethylamine in 200 mL of toluene is added rapidly dropwise (approx. 30min). A suspension is obtained. The P³¹-NMR—after further 2 h ofreaction time—shows that the educt (signal at 150 ppm) is fully reactedand a new product is formed (signal at 123 ppm). After filtration andremoval of the toluene (rotary evaporator) the product is isolated.Yield: 68 g (0.165 mol=96% of theory) of the title compound as a crudeslight yellow oil; P³¹-NMR signals at: 124 ppm (major peak); 123 ppm;Total reaction time: 3 h. % P(calc): 7.47; % P (found): 7.24.

Example 3 Retention of Physical Properties and Color Control ofPolypropylene Homopolymer

A Spheripol® bulk phase polypropylene homopolymer (Profax 6501) fromBasell Corporation, with an initial melt flow rate of ca. 3.4 dg/min(2.16 kg, 230° C.) is used as a representative injection molding graderesin for this example.

The tables below list the amount of additives in parts per million (ppm)based on the overall formulation. The concentration of the variousphosphites are set so that each formulation contains about the samemolar equivalents of phosphorus. Each formulation also contains 500 ppmcalcium stearate as a scavenger for acidic residues and polymerizationcatalyst deactivator. The formulations are prepared by dry blending theappropriate additives with the polymer in a Turbula® blender for twentyminutes followed by melt compounding on a single screw extruder at 450°F. (232° C.) using a polyolefin screw fitted with a Maddock mixingsection under nitrogen. After this initial zero pass compounding, theformulations are submitted to additional extrusion passes at 525° F.(274° C.) with the extruder open to air. The 1^(st), 3^(rd) and 5^(th)extrusion passes are collected for additional testing as describedbelow.

Melt flow rates are measured on a Tinius-Olsen Extrusion Plastometeraccording to ASTM D 1238. Yellowness Index, YI, is measured according toASTM-1295 with a DCI SF600 spectrophotometer, large area view, spectralcomponent included, C illuminant, 20 observer. Gas Fade DiscolorationResistance is measured according to AATCC Test Method 23, using anAtmospheric Fume Chamber Model 8727 from U.S. Research & Testing Co., at60° C. Oven Aging Discoloration Resistance is measured according to ASTMD 3012, with slight modifications, using a Blue M oven running at 60° C.Oxidative Induction Times are assessed using a differential scanningcalorimeter using ASTM D 3895, with slight modifications using analuminum pan instead of a copper pan.

Formulation AO1 P1 P2 P3 P4 P5 P6 P7 P8 NOH A — — — — — — — — — — B 500— — — — — — — — — C 500 1050 — — — — — — — — D 500 — 850 — — — — — — — E500  660 330 — — — — — — — F 500 — — 500 — — — — — — G 500 — — — 750 — —— — — H 500 — — — — 1100 — — — — I 500 — — — — — 1100 — — — J 500 — — —— — — 800 — — K 500 — — — — — — — 680 —

Formulation AO1 P1 P2 P3 P4 P5 P6 P7 P8 BF1 A — — — — — — — — — — L 500— — — — — — — — 200 M 500 500 — — — — — — — 200 N 500 — 400 — — — — — —200 O 500 333 167 — — — — — — 200 P 500 — — 300 — — — — — 200 Q 500 — —— 350 — — — — 200 R 500 — — — — 500 — — — 200 S 500 — — — — — 400 — —200 T 500 — — — — — — 350 — 200 U 500 — — — — — — — 680 200

Tris-nonylcyclohexylphosphite (TNCP), used as a melt processingstabilizer in blends with phenolic antioxidants or with blends withphenolic antioxidants and benzofuranones, performs similarly to otherphosphites, according to the present tests. It is typically better thanTNPP. TNCP may be replaced with the compound of Example 2.

EXAMPLE 4 Retention of Physical Properties and Color Control of LinearLow Density Polyethylene

A Unipol® gas phase linear low density polyethylene copolymer fromExxonMobil Corporation, with an initial melt flow rate of ca. 1 dg/min(2.16 kg, 190° C.) is used as a representative blown film grade resinfor this example.

The tables below list the amount of additives in parts per million (ppm)based on the overall formulation. The concentration of the variousphosphites are set so that each formulation contains about the samemolar equivalents of phosphorus. Each formulation also contains 500 ppmzinc stearate as a scavenger for acidic residues and polymerizationcatalyst deactivator. The formulations are prepared by dry blending theappropriate additives with the polymer in a Turbula® blender for twentyminutes followed by melt compounding on a single screw extruder at 425°F. (218° C.) using a polyolefin screw fitted with a Maddock mixingsection under nitrogen. After this initial zero pass compounding, theformulations are submitted to additional extrusion passes at 500° F.(260° C.) with the extruder open to air. The 1^(st), 2^(nd) and 3^(rd)extrusion passes are collected for additional testing as describedbelow.

Melt flow rates are measured on a Tinius-Olsen Extrusion Plastometeraccording to ASTM D 1238. Yellowness Index, YI, is measured according toASTM-1295 with a DCI SF600 spectrophotometer, large area view, spectralcomponent included, C illuminant, 2° observer. Gas Fade DiscolorationResistance is measured according to MTCC Test Method 23, using anAtmospheric Fume Chamber Model 8727 from U.S. Research & Testing Co., at60° C. Oven Aging Discoloration Resistance is measured according to ASTMD 3012, with slight modifications, using a Blue M oven running at 60° C.Oxidative Induction Times are assessed using a differential scanningcalorimeter using ASTM D 3895, with slight modifications using analuminum pan instead of a copper pan.

Formulation AO2 P1 P2 P3 P4 P5 P6 P7 P8 NOH A — — — — — — — — — — B 500— — — — — — — — — C 500 1050  — — — — — — — — D 500 — 850 — — — — — — —E 500 660 330 — — — — — — — F 500 — — 500 — — — — — — G 500 — — — 750 —— — — — H 500 — — — — 1100 — — — — I 500 — — — — — 1100 — — — J 500 — —— — — — 800 — — K 500 — — — — — — — 680 — L 500 660 — — — — — — — 330

Formulation H1 P1 P2 P3 P4 P5 P6 P7 P8 NOH A — — — — — — — — — — M 500 —— — — — — — — — N 500 1050  — — — — — — — — O 500 — 850 — — — — — — — P500 660 330 — — — — — — — Q 500 — — 500 — — — — — — R 500 — — — 750 — —— — — S 500 — — — — 1100 — — — — T 500 — — — — — 1100 — — — U 500 — — —— — — 800 — — V 500 — — — — — — — 680 — W 500 660 — — — — — — — 330

Tris-nonylcyclohexylphosphite (TNCP), used as a melt processingstabilizer in blends with a hindered phenolic antioxidant or a hinderedamine light stabilizer performs similarly to other phosphites, accordingto the present tests. It is typically better than TNPP. TNCP may bereplaced with the compound of Example 2.

1. A mono-, bis- or tris-nonylcyclohexylphosphite ester of the formulaI, II, III or IV

where R and R′ are independently straight or branched chain alkyl offrom 1 to 24 carbon atoms, or R and R′ together form a 5 or 6 memberedring, where the carbon atoms of said ring are unsubstituted orsubstituted by one or two straight or branched chain alkyl groups offrom 1 to 24 carbon atoms.
 2. A mono-nonylcyclohexylphosphite esteraccording to claim 1 of the formula I.
 3. Amono-nonylcyclohexylphosphite ester according to claim 1 of the formula


4. A mono-nonylcyclohexylphosphite ester according to claim 1 of theformula II


5. A bis-nonylcyclohexylphosphite ester according to claim 1 of theformula III.
 6. A bis-nonylcyclohexylphosphite ester according to claim1 of the formula III where R is methyl, ethyl or hexyl.
 7. An esteraccording to claim 1 which is tris-nonylcyclohexylphosphite ester offormula IV.
 8. A polyolefin composition stabilized against thedeleterious effects of melt processing, heat aging and exposure tocombustion products of natural gas, which composition comprises at leastone polyolefin and an effective stabilizing amount of one or more mono-,bis- or tris-nonylcyclohexylphosphite esters of formula I, II, III or IVaccording to claim
 1. 9. A composition according to claim 8 comprisingan effective stabilizing amount of tris-nonylcyclohexylphosphite.
 10. Acomposition according to claim 8 where the polyolefin is polypropylene,polyethylene or thermoplasitc polyolefin.
 11. A composition according toclaim 8 where the mono-, bis- or tris-nonylcyclohexylphosphite estersare present from about 0.01% to about 5% by weight, based on the weightof the polyolefin.
 12. A composition according to claim 8 where themono-, bis- or tris-nonylcyclohexylphosphite esters are present at alevel of less than about 3% by weight, based on the weight of thepolyolefin.
 13. A composition according to claim 8 further comprising atleast one hindered phenolic antioxidant selected from the groupconsisting of tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate,1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,the calcium salt of the monoethyl ester of3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid, pentaerythritoltetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] andoctadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.
 14. Acomposition according to claim 8 further comprising at least onehindered amine light stabilizer selected from the group consisting of

where n is an integer such that the total molecular weight is aboveabout 1000 g/mole.
 15. A composition according to claim 8 furthercomprising at least one hydroxylamine stabilizer selected from the groupconsisting of Hydroxylamine stabilizers are for exampleN,N-dibenzylhydroxylamine, N,N-diethylhydroxylamine,N,N-dioctylhydroxylamine, N,N-dilaurylhydroxylamine,N,N-didodecylhydroxylamine, N,N-ditetradecylhydroxylamine,N,N-dihexadecylhydroxylamine, N,N-dioctadecylhydroxylamine,N-hexadecyl-N-tetradecylhydroxylamine,N-hexadecyl-N-heptadecylhydroxylamine,N-hexadecyl-N-octadecylhydroxylamine,N-heptadecyl-N-octadecylhydroxylamine, N-methyl-N-octadecylhydroxylamineand N,N-di(hydrogenated tallow)hydroxylamine.
 16. A compositionaccording to claim 8 further comprising at least one benzofuranonestabilizer selected from the group consisting of3-(4-(2-acetoxyethoxy)phenyl)-5,7-di-tert-butyl-benzofuran-2-one,5,7-di-tert-butyl-3-(4-(2-stearoyloxyethoxy)phenyl)benzofuran-2-one,3,3′-bis(5,7-di-tert-butyl-3-(4-(2-hydroxyethoxy)phenyl)benzofuran-2-one),5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one,3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one,3-(3,4-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one or3-(2,3-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one.
 17. Acomposition according to claim 8 further comprising at least one otherorganic phosphorus stabilizer.
 18. A composition according to claim 8further comprising at least one other organic phosphorus stabilizerselected from the group consisting of triphenyl phosphite, diphenylalkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, distearylpentaerythritol diphosphite, bis(2,4-di-α-cumylphenyl) pentaerythrtitoldiphosphite, tris(2,4-di-tert-butylphenyl) phosphite, diisodecylpentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bisisodecyloxy-pentaerythritol diphosphite,bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite,bis(2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite, tristearylsorbitol triphosphite, tetrakis (2,4-di-tert-butylphenyl)4,4′-biphenylene-diphosphonite,6-isooctyloxy-2,4,8,10-tetra-tert-butyl-dibenzo[d,f][1,3,2]dioxaphosphepin,6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzo[d,g][1,3,2]dioxaphosphocin,bis(2,4-di-tert-butyl-6-methylphenyl) methyl phosphite,bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite,2,2′,2″-nitrilo[triethyltris(3,3′5,5′-tetra-tert-butyl-1,1′-biphenyl-2,2′-diyl)phosphite],bis(2,4-di-t-butylphenyl) octylphosphite,poly(4,4′-{2,2′-dimethyl-5,5′-di-t-butylphenylsulfide-}octylphosphite),poly(4,4′{-isopropylidenediphenol}-octylphosphite),poly(4,4′-{isopropylidenebis[2,6-dibromophenol]}-octylphosphite),poly(4,4′-{2,2′-dimethyl-5,5′-di-t-butylphenylsulfide}-pentaerythrityldiphosphite),


19. A composition according to claim 8 further comprisingtris(nonylphenyl) phosphite or tris(2,4-di-tert-butylphenyl) phosphite.20. A process for stabilizing a polyolefin composition against thedeleterious effects of melt processing, heat aging and exposure tocombustion products of natural gas, which process comprisesincorporating into or applying to said polyolefin composition aneffective stabilizing amount of one or more mono-, bis- ortris-nonylcyclohexylphosphite esters of the formula I, I, III or IVaccording to claim 1.